Detection: Detect Certipy File Modifications

Updated Date: 2024-11-13 ID: 7e3df743-b1d8-4631-8fa8-bd5819688876 Author: Steven Dick Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the use of the Certipy tool to enumerate Active Directory Certificate Services (AD CS) environments by identifying unique file modifications. It leverages endpoint process and filesystem data to spot the creation of files with specific names or extensions associated with Certipy's information gathering and exfiltration activities. This activity is significant as it indicates potential reconnaissance and data exfiltration efforts by an attacker. If confirmed malicious, this could lead to unauthorized access to sensitive AD CS information, enabling further attacks or privilege escalation within the network.

 1
 2| tstats `security_content_summariesonly` count min(_time) AS firstTime max(_time) AS lastTime values(Processes.process_current_directory) as process_current_directory FROM datamodel=Endpoint.Processes where Processes.action="allowed" BY _time span=1h Processes.user Processes.dest Processes.process_id Processes.process_name Processes.process Processes.process_path Processes.parent_process_name Processes.parent_process Processes.process_guid Processes.action 
 3|`drop_dm_object_name(Processes)` 
 4| join max=0 dest process_guid [
 5| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Filesystem where Filesystem.file_name IN ("*_certipy.zip", "*_certipy.txt", "*_certipy.json", "*.ccache") by Filesystem.file_create_time Filesystem.process_id Filesystem.process_guid Filesystem.file_name Filesystem.file_path Filesystem.dest 
 6| `drop_dm_object_name(Filesystem)` ] 
 7| fields firstTime lastTime user dest file_create_time file_name file_path parent_process_name parent_process process_name process_path process_current_directory process process_guid process_id 
 8| where isnotnull(file_name) 
 9| `security_content_ctime(firstTime)` 
10| `security_content_ctime(lastTime)` 
11| `detect_certipy_file_modifications_filter`

Data Source

Name Platform Sourcetype Source
Sysmon EventID 1 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Sysmon EventID 11 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
detect_certipy_file_modifications_filter search *
detect_certipy_file_modifications_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1649 Steal or Forge Authentication Certificates Credential Access
T1560 Archive Collected Data Collection
Exploitation
DE.CM
CIS 10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints as well as file creation or deletion events.

Known False Positives

Unknown

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

Suspicious files $file_name$ related to Certipy detected on $dest$

Risk Object Risk Object Type Risk Score Threat Objects
dest system 45 process_name, file_name
user user 45 process_name, file_name

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational XmlWinEventLog

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 5